The proposed work is directed at the commercialization of a stretchable microelectrode array (BMSEED's sMEA), a new tool that provides enhanced capabilities to simultaneously interface mechanically and electrically with cell cultures in vitro. The mechanical stretching of neurons in the brain or spinal cord is often te root cause of traumatic brain injury (TBI) and spinal cord injury (SCI). Mechanical strain is also an important cue for the differentiation of stem cells. It is currently not possible for in vitro models of TBI, SCI, or tissue engineering to carry out electrophysiological measurements while stretching the cells. BMSEED's sMEAs will enable this capability by having microelectrodes that stretch and relax elastically with the cells, allowing to (a) record and stimulate electrophysiological activity from the same location before, during, and after stretching the cells (b) investigate the cumulative effects of repeated, sub-threshold injuries over time (e.g., repetitive concussions), and (c) normalize post-injury neural activity to pre-injury levels. These capabilities will greatly improve research on the evaluation of drugs and other treatment strategies to minimize the damage to the nervous system after an injury, saving time, money and lives of animals. BMSEED's sMEA could also be an effective tool for controlling the mechanically-induced differentiation of stem cells into electrophysiologically active cells, such a neurons or cardiomyocytes, which is a major goal of regenerative medicine. BMSEED's sMEA consists of an elastomeric substrate with embedded microelectrodes, and an interface to the data acquisition system. Our previous research has demonstrated the capabilities of sMEA prototypes in traumatic brain injury research. Therefore, this proposed work aims to develop this sMEA into a commercial product by improving the current fabrication process. The first specific aim of this proposal is therefore to reduce the cost to produce sMEA through process simplification and parallel processing. We will (a) evaluate three methods to deposit the gold film with respect to their cost-effectiveness and reliability, (b) replace the current lithographic methd to produce the microelectrode pattern with shadow mask patterning, and (c) replace the manual process to electroplate the microelectrodes with an automated one. The second specific aim is to characterize these low- cost sMEAs for traumatic brain injury research. We will first compare sMEAs produced with the three gold deposition methods for (i) their biocompatibility, (ii) their functionality, (iii) the maximum strain at which they remain functional, and (iv) how many times they can be re-used. We will then fabricate 70 sMEAs with the process that produces the highest quality sMEAs, and assess their repeatability using the same criteria. The results of this aim will also apply to other applications such as spinal cord injury and tissue engineering. The successful completion of this project will provide a cost-effective method to produce sMEAs. The long- term goal of BMSEED is to extend the application of the sMEAs' soft and compliant microelectrodes to in vivo neural interfaces in mechanically active (e.g., near the heart) and very soft (e.g., the brain) environment.